[PATCH] ar5523: Fix use-after-free on ar5523_cmd() timed out
From: Shigeru Yoshida
Date: Sun Oct 09 2022 - 14:32:51 EST
syzkaller reported use-after-free with the stack trace like below [1]:
[ 38.960489][ C3] ==================================================================
[ 38.963216][ C3] BUG: KASAN: use-after-free in ar5523_cmd_tx_cb+0x220/0x240
[ 38.964950][ C3] Read of size 8 at addr ffff888048e03450 by task swapper/3/0
[ 38.966363][ C3]
[ 38.967053][ C3] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 6.0.0-09039-ga6afa4199d3d-dirty #18
[ 38.968464][ C3] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014
[ 38.969959][ C3] Call Trace:
[ 38.970841][ C3] <IRQ>
[ 38.971663][ C3] dump_stack_lvl+0xfc/0x174
[ 38.972620][ C3] print_report.cold+0x2c3/0x752
[ 38.973626][ C3] ? ar5523_cmd_tx_cb+0x220/0x240
[ 38.974644][ C3] kasan_report+0xb1/0x1d0
[ 38.975720][ C3] ? ar5523_cmd_tx_cb+0x220/0x240
[ 38.976831][ C3] ar5523_cmd_tx_cb+0x220/0x240
[ 38.978412][ C3] __usb_hcd_giveback_urb+0x353/0x5b0
[ 38.979755][ C3] usb_hcd_giveback_urb+0x385/0x430
[ 38.981266][ C3] dummy_timer+0x140c/0x34e0
[ 38.982925][ C3] ? notifier_call_chain+0xb5/0x1e0
[ 38.984761][ C3] ? rcu_read_lock_sched_held+0xb/0x60
[ 38.986242][ C3] ? lock_release+0x51c/0x790
[ 38.987323][ C3] ? _raw_read_unlock_irqrestore+0x37/0x70
[ 38.988483][ C3] ? __wake_up_common_lock+0xde/0x130
[ 38.989621][ C3] ? reacquire_held_locks+0x4a0/0x4a0
[ 38.990777][ C3] ? lock_acquire+0x472/0x550
[ 38.991919][ C3] ? rcu_read_lock_sched_held+0xb/0x60
[ 38.993138][ C3] ? lock_acquire+0x472/0x550
[ 38.994890][ C3] ? dummy_urb_enqueue+0x860/0x860
[ 38.996266][ C3] ? do_raw_spin_unlock+0x16f/0x230
[ 38.997670][ C3] ? dummy_urb_enqueue+0x860/0x860
[ 38.999116][ C3] call_timer_fn+0x1a0/0x6a0
[ 39.000668][ C3] ? add_timer_on+0x4a0/0x4a0
[ 39.002137][ C3] ? reacquire_held_locks+0x4a0/0x4a0
[ 39.003809][ C3] ? __next_timer_interrupt+0x226/0x2a0
[ 39.005509][ C3] __run_timers.part.0+0x69a/0xac0
[ 39.007025][ C3] ? dummy_urb_enqueue+0x860/0x860
[ 39.008716][ C3] ? call_timer_fn+0x6a0/0x6a0
[ 39.010254][ C3] ? cpuacct_percpu_seq_show+0x10/0x10
[ 39.011795][ C3] ? kvm_sched_clock_read+0x14/0x40
[ 39.013277][ C3] ? sched_clock_cpu+0x69/0x2b0
[ 39.014724][ C3] run_timer_softirq+0xb6/0x1d0
[ 39.016196][ C3] __do_softirq+0x1d2/0x9be
[ 39.017616][ C3] __irq_exit_rcu+0xeb/0x190
[ 39.019004][ C3] irq_exit_rcu+0x5/0x20
[ 39.020361][ C3] sysvec_apic_timer_interrupt+0x8f/0xb0
[ 39.021965][ C3] </IRQ>
[ 39.023237][ C3] <TASK>
In ar5523_probe(), ar5523_host_available() calls ar5523_cmd() as below
(there are other functions which finally call ar5523_cmd()):
ar5523_probe()
-> ar5523_host_available()
-> ar5523_cmd_read()
-> ar5523_cmd()
If ar5523_cmd() timed out, then ar5523_host_available() failed and
ar5523_probe() freed the device structure. So, ar5523_cmd_tx_cb()
might touch the freed structure.
This patch fixes this issue by canceling in-flight tx cmd if submitted
urb timed out.
Link: https://syzkaller.appspot.com/bug?id=9e12b2d54300842b71bdd18b54971385ff0d0d3a [1]
Reported-by: syzbot+95001b1fd6dfcc716c29@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Shigeru Yoshida <syoshida@xxxxxxxxxx>
---
drivers/net/wireless/ath/ar5523/ar5523.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/net/wireless/ath/ar5523/ar5523.c b/drivers/net/wireless/ath/ar5523/ar5523.c
index 6f937d2cc126..ce3d613fa36c 100644
--- a/drivers/net/wireless/ath/ar5523/ar5523.c
+++ b/drivers/net/wireless/ath/ar5523/ar5523.c
@@ -241,6 +241,11 @@ static void ar5523_cmd_tx_cb(struct urb *urb)
}
}
+static void ar5523_cancel_tx_cmd(struct ar5523 *ar)
+{
+ usb_kill_urb(ar->tx_cmd.urb_tx);
+}
+
static int ar5523_cmd(struct ar5523 *ar, u32 code, const void *idata,
int ilen, void *odata, int olen, int flags)
{
@@ -280,6 +285,7 @@ static int ar5523_cmd(struct ar5523 *ar, u32 code, const void *idata,
}
if (!wait_for_completion_timeout(&cmd->done, 2 * HZ)) {
+ ar5523_cancel_tx_cmd(ar);
cmd->odata = NULL;
ar5523_err(ar, "timeout waiting for command %02x reply\n",
code);
--
2.37.3